| AVS 54th International Symposium | |
| Surface Science | Friday Sessions |
| Session SS2+EM+TF-FrM |
| Session: | Organic Films II: Semiconductors and C@sub 60@ |
| Presenter: | G. Pirug, Forschungszentrum Jülich, Germany |
| Authors: | G. Pirug, Forschungszentrum Jülich, Germany M. Kazempoor, Forschungszentrum Jülich, Germany J. Myslivecek, Charles University in Prague, Czech Republic B. Voigtländer, Forschungszentrum Jülich, Germany |
| Correspondent: | Click to Email |
The adsorption of ferrocene (Fe(C5H5)2) on Au(111) surfaces has been studied spectroscopically applying HREELS and XPS as well as structurally by means of LEED and STM under UHV conditions. The vibrational modes observed by HREELS indicate reversible molecular adsorption of ferrocene at temperatures of about 110 K. The corresponding frequencies are not significantly shifted with respect to IR or Raman data from solution, indicating a weak adsorbate - substrate interaction. Multilayer adsorption can be distinguished from the physisorbed first layer based on the sequential appearance and relative intensity changes of vibrational modes. In the monolayer regime vibrational modes with a perpendicular dipole moment from ferrocene molecules with an upright standing molecular axis dominate, as concluded from on- and off-specular HREEL spectra applying the surface dipole selection rules. Dissociation into cyclopentadienyl ring radicals (C5H5) can be excluded due to the missing related vibrational losses, such as the wagging mode expected at about 760 cm-1. For multilayer coverages the orientation of the condensed ferrocene molecules is no longer exclusively perpendicular to the surface which results in the appearance of additional vibrational losses. Molecular self assembly yields a well ordered surface structure as shown by topographical STM pictures and LEED pattern.